The invention relates to a boring element of the ground boring device with a housing and a transmitter arranged in a receptacle of the housing.
It is known to provide ground boring devices with a transmitter for localizing the signals transmitted by the transmitter with a receiving unit arranged above ground to thereby determine the position of the ground boring device in the ground. The course of the borehole can then be continuously monitored and corrected—if this is a steerable ground boring device—in the event of a deviation from the desired course by rerouting the ground boring device.
Various embodiments of ground boring devices are known in the art. Frequently, so-called earth rockets are used to create horizontal boreholes in the ground, i.e. boreholes which extend essentially in the ground near the surface in the horizontal direction. These are self-propelled percussion boring devices which are equipped with a percussion drive operating with compressed air, with the required compressed drive air being supplied via a rear supply hose. The earth rocket may be steered, for example, by adjusting the tip of the drill head, which causes a lateral deflection leading to an arcuate course of the borehole. A steerable earth rocket of this type is disclosed, for example, in DE 199 47 645 C1.
Also known are horizontal boring devices where a drill head arranged at the front end of a drill pipe is advanced through the ground by pushing and rotating the drill head with a drive device located in a pit, in a trench or on the surface. The horizontal boring device of this type can be steered by constructing the drill head asymmetrically, for example with an sloped font face, so that a lateral force is generated when the drill head is advanced only by pushing, i.e. without rotation, causing the desired lateral deflection of the drill head. This lateral force is compensated on the average for a straight borehole by additionally driving the drill head with a uniform rotation.
Also in such horizontal boring device based on a drill pipe, the advance of the drill head may be supported by applying percussions. This may be accomplished —as with the earth rocket—by an internal percussion drive; however, in most cases the percussions are generated by an external percussion drive and transmitted to the drill head via the drill pipe. This obviates the need to integrate a percussion drive into the drill head which frequently has limited dimensions.
The drill head for such horizontal boring device based on drill pipes is disclosed, for example, in DE 195 34 806 A1. The drill head includes a sloped a drill head referred to as steering head and a connected housing having a receptacle for a transmitter. The housing has on its end opposing the sloped drill head an exterior thread configured to screw the housing into a first pipe section of the drill pipe. The transmitter is supported inside the receptacle of the cylindrical housing for movement along its longitudinal-axial direction, with each end of the transmitter contacting a respective buffer in order to dampen the relative movement of the transmitter inside the receptacle of the housing caused by the percussions acting on the drill pipe. The magnitude of the force impulses applied to the transmitter can thereby be reduced significantly, which is necessary because this transmitter is typically a sensitive electronic component.
An integration of a transmitter in an earth rocket of similar construction is disclosed, for example, in DE 198 23 629 A1, which proposes to retrofit an earth rocket with a drill head adapter in which the transmitter is integrated. The ends of the transmitter are hereby embedded in the corresponding receptacle in the boring tool of the drill head adapter between two damping elements.
It has been observed in conventional ground boring devices with integrated transmitter that the stress on the transmitter caused by percussions cannot always be sufficiently reduced, thus resulting in damage caused by the operation of the percussion ground boring device.
Based on this state of the art, it was therefore the object of the invention to provide an improved integration of a transmitter in a ground boring device.